1. Field of the Invention
The invention concerns a device for damping vibrations or oscillations, especially a torsional vibration damper to dampen rotating components, a drive system for vehicles and also a process for controlling the hysteresis of a vibration damping device.
2. Description of the Related Art
Devices to dampen vibrations are known in numerous applications. See, for example, the publication from Borg Warner Automotive: Torsionsschwingungsdxc3xa4mpfer (Torsional Vibration Dampers), 0691W, 1991.
The expression xe2x80x9cvibration damping devicexe2x80x9d should be interpreted in the most general manner. In general, a type of elastic clutch is used, which is arranged between two components in a drive train, for example an internal combustion engine and a transmission. Such devices serve to hinder vibrations from the internal combustion engine from transferring to the rest of the drive train. These must be set in such a manner that the critical torque of the entire dimensional system is far enough below the operational area.
The known vibration damping device includes at least two elements: a primary element and a secondary element, which can be coupled together using a spring mechanism, and which can be rotated against each other circumferentially within a limited angle. The spring mechanism also ideally includes a number of springs, which are ideally arranged at a set distance from each other, in a circle coaxial to the damper axle in the circumference direction. Due to the spring clutch, a transfer of torque occurs, through which a damping affect is additionally achieved in specific measure, due to the spring characteristics. When such a device is used in drive trains for vehicles, it has been shown that the availability of a high friction moment in the drive train is necessary to decrease the vibration amplitudes in the resonant range. However, the result of this is a decrease in driving comfort at higher rotational speeds.
Dependent upon the layout of such devices to dampen vibrations, especially the amount of spring rigidity and the size of the secondary mass, problems were observed in starting the propelling engine, which become obvious during winding up or stretching the damper and the following overshoot or overswing, where the component strength could be surpassed.
Therefore, the invention is based on the assignment to further develop a vibration damping device in such a manner that the disadvantages in prior art are avoided. Specifically, an optimal adjustment to concrete uses towards high operational safety as well as availability should be achieved in regards to the vibrations that need to be dampened over the entire operational area or a part of the operational area, especially in the area of lower engine rotational speeds. The design layout should be characterized by minimal need for space, simple assembly and above all, minimal expenses.
The vibration damping device includes at least two elementsxe2x80x94a primary element and a secondary elementxe2x80x94which may be movable to a limited extent relative to each other and in the case of a torsional vibration damper can be rotated to a limited extent in the circumference direction in relation to each other. The first primary element and the second secondary element can be coupled together using a spring coupling. The means to realize the spring coupling include at least one spring device, and in the case of a torsional vibration damper ideally a number of spring devices, arranged circumferentially around the two elementsxe2x80x94the primary and secondary elements.
Based on the invention, at least one adjustable coupling or clutch device is integrated in the vibration damping device, including at least two elements rubbing against each otherxe2x80x94a first element and a second elementxe2x80x94, which bring the primary and secondary elements (3.1, 3.2) into frictional contact with each other. In addition, a power generator is assigned to the elements rubbing against each other to create a controlled friction contact between the elements rubbing against each other. Control should be interpreted as not only the steerability but also the controllability of the friction engagement or an interference of these possibilities The power generator ideally includes a control device, which functions as adjustor of a control device, ideally an electronic one.
The terms xe2x80x9cprimary elementxe2x80x9d and xe2x80x9csecondary elementxe2x80x9d refer to the arrangement and function of these elements in the power flow direction in the traction operation of a propelling engine or propelling unit of the drive. The primary element is connected with the input side, while the secondary element is coupled with the output side. The functions of the moment of force or torque inlet or outlet could, however, depending on operation of the drive train (traction operation or tow operation), also be taken over by a different element, i.e. these are not tied to the primary or secondary element.
There are numerous possibilities in regards to detailed design applications of the primary element and the secondary elements. Ideally, these are mainly designed to be disk-shaped.
An especially preferred design with a minimal number of components has at least one element of the coupling or clutch device being formed by one of the two elementsxe2x80x94primary element or secondary element. However, separate frictional engaging elements are also possible.
The inventive solution makes it possible to influence the achieved damping effect in the vibration damping device, in regards to its magnitude size and/or operation over the entire operational area of the propelling engine, and thereby to control the parameters of the vibration amplitudes, in dependence on certain physical parameters in the drive train, for example the speed and/or load of the propelling engine or unit, that cause the friction force or friction moment using the clutch device (friction clutch).
The control/steering conversion technology determines the point in time to operate the friction clutch. In an additional aspect of the invention, the amount of pressure can also be control/steered in a targeted manner to create a corresponding friction moment. This requires the use of a corresponding control/steering concept in regards to the closing the friction clutch and/or the operational force to be used.
Ideally, the secondary element includes in its design at least two lateral disks that can ideally be torsionally fixed to (frictionally engage) each other. The primary element is then arranged axially between the two lateral disks. One element of the clutch device is formed by at least one of the two lateral disks of the secondary element. Ideally, the friction contact of the friction clutch occurs with one of the two elements, here the secondary element, having an even force effect, including the other of the two elements, in this case the primary element. An additional element of the clutch device is formed by a piston element that is torsionally fixed to the primary element, in the case of a torsional vibration damper, and that can be moved in an axial direction. The striking surface of the elements rubbing together which are formed from the lateral disks of the secondary element, are arranged to the surfaces facing the primary element, while the striking surfaces of the elements rubbing together which are formed by the primary element and the piston element are each arranged on the lateral surfaces of these elements, that face the inner surface of the secondary element or the surfaces opposite the lateral disks.
Ideally, the clutch device is a disk clutch.
This means that the striking or frictional engaging surfaces are arranged on the disk-shaped elements. The execution of the striking surfaces are carried out radially in such a manner, that the striking surfaces of at least the elements having the striking surfaces which are immediately in friction contact with each other are ideally arranged the same radial distance from each other.
There are numerous possibilities in regards to execution and function of the means to create an adjustable pressure. In an especially beneficial design, the friction engagement occurs through hydraulic operation of the friction clutch. Alternatively, the operation can occur using electro-magnetics, especially rheo-magnetics. For that, at least one operational device is present for at least the indirect realization of the friction contact between the elements rubbing together. This device has a pressure device that strikes a pressure chamber in order to produce the friction contact between the elements that are rubbing together, and that moves one of the rubbing elements in the opposite axial direction of the other, and in doing so achieves contact pressure. The pressure chamber is formed between the piston element that is torsionally fixed to the primary element and can be moved axially and the primary element. In addition, means to seal the pressure chamber in radial direction are necessary. The pressure medium is ideally provided through line channels that are arranged in the connection elements of the vibration damping device. These can either be rotating or stationary components. This execution has the benefit that the pressure device can be integrated in other operational or pressure supply devices and can use their channels.
The seals ideally comprise an elastic seal device which can counteract the axial changes in dimensions of the pressure chamber while maintaining complete sealing function.
In order provide quick additional damping, the pressure chamber ideally should constantly be full. However, this leads to a minimal friction moment while the friction clutch is not in use, due to the centrifugal force of the adjusted fluid pressure, and along with that an additional damping effect is achieved. In order to avoid this additional damping effect, means to avoid the influence of the centrifugal force in the pressure chamber are present. These include a second pressure chamber, which is arranged on the primary element""s lateral surface that is turned away from the first pressure chamber and is connected to the first pressure chamber by at least one overflow channel. The second pressure chamber is axially limited by an extension of the second lateral disk of the secondary element that reaches radially to the rotation axle.
The device to dampen, especially the integrated friction clutch, can be adjustable and/or steerable and/or controllable. It has a control device with corresponding regulator. The regulator has at least one inlet, which is connected with a device to at least indirectly access a load and/or torque of a propelling engine/component with an at least indirectly characterizing size, and at least one outlet which is coupled with a regulator for at least indirect influence of the pressure in the pressure chamber.
The inventive solution is ideally used in drive trains of vehicles. However, stationary applications are also possible.
For that, the primary element can at least be coupled indirectly with the propelling engine/component during traction, and the secondary element can be torsionally fixed to the drive.
The vibration damping device, according to the invention, is characterized by a minimal need for space. By steering the damping relationship through simple shutting off of the additional damping effect or with targeted control/steering, the damping relationship can be optimally adjusted for the demands in the drive train for all operational areas. This will especially improve driving comfort when used in vehicles. Additionally, component wear is reduced.
The invention also includes a procedure to control the hysteresis of a vibration damping device where the adjustment of friction strength, dependent on the load and/or the speed of the propelling component, occurs at least in indirectly described amounts. Thus it is possible to shut off the friction clutch in operational areas of minimal load and/or high speeds of the propelling engine, while in operational areas of large loads and/or low speeds of the propelling component, the friction clutch in the vibration damping device is turned on.